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DE-112024002857-T5 - Optical CRA detector unit, multispectral sensor system and camera system

DE112024002857T5DE 112024002857 T5DE112024002857 T5DE 112024002857T5DE-112024002857-T5

Abstract

An optical CRA detector unit (14) with an optical CRA sensor (26) arranged on a substrate (22), wherein the optical CRA sensor (26) comprises a number of CRA detector pixels (30) with the same spectral sensitivity, each generating a radiation intensity signal, wherein the radiation intensity signals generated by the CRA detector pixels (30) are provided to generate a parameter characteristic of the principal beam angle (CRA) of the radiation intensity of the CRA detector unit (14), enabling a particularly compact and miniaturized arrangement. According to the invention, this is achieved by providing an aperture element (32) which is arranged above the optical CRA sensor (26) with respect to the substrate (22), wherein the aperture element (32) comprises a flat, laterally extending refractive element (34) which defines a top (36) and a bottom (38), wherein the top and the bottom (36, 38) are provided with an upper aperture layer (40) and a lower aperture layer (42), respectively, and wherein the upper aperture layer (40) is provided with an upper aperture (44) and the lower aperture layer (46) with a lower aperture (46) which has a lateral size of at least the lateral size of the upper aperture (44).

Inventors

  • Gunter Siess

Assignees

  • AMS-OSRAM AG

Dates

Publication Date
20260513
Application Date
20240423
Priority Date
20230704

Claims (17)

  1. An optical CRA detector unit (14) comprising an optical CRA sensor (26) arranged on a substrate (22), wherein the optical CRA sensor (26) comprises a number of CRA detector pixels (30) with the same spectral sensitivity, each generating a radiation intensity signal, wherein the radiation intensity signals generated by the CRA detector pixels (30) are provided to generate a parameter characteristic of the principal beam angle (CRA) of the radiation intensity of the CRA detector unit (14), and comprising an aperture element (32) provided above the optical CRA sensor (26) with respect to the substrate (22), wherein the aperture element (32) is a flat, laterally extending refractive element (34) comprises a top surface (36) and a bottom surface (38), wherein the top and bottom surfaces (36, 38) are provided with an upper aperture layer (40) and a lower aperture layer (42), respectively, and wherein the upper aperture layer (40) is provided with an upper aperture (44) and the lower aperture layer (46) is provided with a lower aperture (46) having a lateral size of at least the lateral size of the upper aperture (44).
  2. The optical CRA detector unit (14) according to Claim 1 , wherein the CRA detector pixels (30) are arranged in a sensor array within a base plane defined by at least three of the CRA detector pixels (30).
  3. The optical CRA detector unit (14) according to Claim 2 , wherein a number of the CRA detector pixels (30o) are arranged in a peripheral region of the sensor arrangement and at least one of the CRA detector pixels (30c) is arranged in a central region of the sensor arrangement within the basal plane.
  4. Optical CRA detector unit (14) according to Claim 3 , wherein each of the CRA detector pixels (30o) located in the periphery of the sensor array is associated with at least one other of the CRA detector pixels (30o) located in the periphery of the sensor at a position opposite to the center of the sensor array.
  5. The optical CRA detector unit (14) according to one of the Claims 2 until 4 , where the aperture width (w) of the lower aperture (46) is smaller than the lateral size (W) of the sensor array in the base plane.
  6. Optical CRA detector unit (14) according to one of the Claims 1 until 5 , wherein each of the CRA detector pixels (30) consists of only one photon measurement unit, preferably a photodiode.
  7. Optical CRA detector unit (14) according to one of the Claims 1 until 6 , further comprising a measuring unit configured to provide sensor signals generated by the optical sensor (26), wherein the measuring unit is arranged to calculate the parameter characteristic of the principal beam angle (CRA) based on the calculation of the ratio of the radiation intensity sensor signals generated by any two CRA detector pixels (30).
  8. Optical CRA detector unit (14) according to one of the Claims 1 until 7 , wherein the refractive element (34) is a glass element.
  9. Optical CRA detector unit (14) according to one of the Claims 1 until 8 , wherein the aperture element (32) with its lower aperture layer (42) is mounted directly on the substrate (22) and the optical sensor (26).
  10. Multispectral sensor system (10) comprising an optical CRA detector unit (14) according to one of the Claims 1 until 9 and a spectral detector unit (12), wherein the spectral detector unit (12) comprises an optical spectral sensor (50) arranged on a substrate (22) to detect received photons, and wherein the spectral sensor (50) comprises a number of multispectral sensor pixels (52), each generating a multispectral sensor signal as part of one of a number of detector channels (56), and an aperture element (32) provided above the spectral sensor (50) with respect to the spectral substrate (22), wherein the aperture element (32) comprises a flat, laterally extending refractive element (34) defining a top (36) and a bottom (38), wherein: - the top and bottom surfaces (36, 38) are provided with an upper aperture layer (40) and a lower aperture layer (42), respectively, - the upper aperture layer (40) and the lower aperture layer (42) Aperture layer (42) is provided with a number of upper multispectral apertures (58) and lower multispectral apertures (60), wherein the upper multispectral apertures (58) and the lower multispectral apertures (60) are arranged in pairs, forming a number of double apertures (62), such that in each double aperture (62) the upper multispectral aperture (58) is arranged above its corresponding lower multispectral aperture (60), and - for each of the detector channels (56) a separate double aperture (62) is provided for it.
  11. Multispectral sensor system (10) according to Claim 10 , wherein each of the detector channels (56) of the spectral sensor (50) comprises at least one of the multispectral pixels (52) and an associated optical filter (54).
  12. Multispectral sensor system (10) according to Claim 11 , wherein for at least one of the channels (56) the optical filter (54) is provided on the top of the upper multispectral aperture (58) of the associated double aperture (62).
  13. Multispectral sensor system (10) according to one of the Claims 10 until 12 , wherein the aperture element (32) with its lower aperture layer (42) is mounted directly on the substrate (22) and the optical sensor (50).
  14. The multispectral sensor system (10) according to one of the Claims 10 until 13 , wherein the multispectral sensor channels (56) each have different spectral transmission properties.
  15. The multispectral sensor system (10) according to one of the Claims 10 until 14 , wherein the optical CRA sensor (26) of the optical CRA detector unit (14) and the optical spectral sensor (50) of the spectral detector unit (12) are arranged on the same substrate (22) and that the same aperture element (32) is provided over the optical CRA sensor (26) of the optical CRA detector unit (14) and the optical spectral sensor (50) of the spectral detector unit (12).
  16. Multispectral sensor system (10) according to one of the Claims 10 until 15 , dt designed as an ambient light sensor (4).
  17. Camera system (1) with an ambient light sensor (4) according to Claim 16 .

Description

Technical background of the invention The invention relates to an optical or spectral CRA detector unit. In particular, the invention relates to an optical CRA detector unit comprising an optical CRA sensor arranged on a substrate to detect received photons, wherein the optical sensor comprises a number of CRA sensor pixels, each generating an irradiation signal, and wherein the irradiation sensor signals generated by the CRA detector pixels are provided to generate a parameter characteristic of the angle of incidence of the irradiation of the CRA detector unit. The invention further relates to a multispectral sensor system comprising such an optical CRA detector unit and a camera system comprising such an optical CRA sensor. background Optical or multispectral sensors are increasingly used in diverse technology fields such as smartphones and mobile devices, smart homes and buildings, industrial automation, medical technology, connected vehicles, and more. At the same time, sensor data is becoming increasingly complex and must meet high accuracy requirements. Furthermore, color detection and spectral light sensing at the chip level find numerous applications in color recognition, data authentication, spectroscopy, and other optical detection applications in both industrial and consumer sectors. In several key applications, particularly for cameras, such sensors are used as ambient light sensors for automatic white balance, providing crucial background information for appropriate correction functions and thus improving overall image quality. Common multispectral sensors are often based on an array of pixels and on-pixel filters for each pixel. For spectroscopic applications, the filters can be chosen to have linearly independent filter characteristics. To achieve an accurate spectral measurement of a specific source, the incident radiation should be known to compensate for the different responses of individual pixels. In this way, the amplitude of a pixel's spectral signal can be used to calculate a spectral reconstruction of the light source under investigation. Typically, multispectral sensors also include interference filters specifically designed for the application. A homogeneous distribution of the incident radiation on the pixel array is an ideal condition. In real systems, however, the actual irradiances measured at the sensor level can vary between different channels due to geometric effects that limit the individual field of view (FOV), the dominant angle of incidence or the chief ray angle (CRA) of the incident radiation, and other factors. Geometric effects in such systems can be caused by misalignments of individual components due to manufacturing tolerances, etc. Particularly when used in ambient light sensors, the homogeneity of the incident light distribution at the detector level can be of paramount importance. To ensure a highly reliable homogeneous distribution, diffusers can be positioned in front of the pixels to mix the incident light as effectively as possible and direct it homogeneously, ideally in a Lambertian pattern, to the sensor array. Furthermore, the spectral sensitivity of a multispectral sensor based on an interference filter is highly dependent on the angular distribution of the light incident on the detector array. Especially with interference filters, their angle-dependent transmission properties must be taken into account to obtain accurate results. This is another important reason for using diffusers to ensure a consistently similar angular distribution. In general, ambient light sensor systems are expected to provide reliable relative measurements between the individual channels of the sensor using such an arrangement and a (nearly) Lambertian diffuser, regardless of the direction or angle of the incident light. This reliable measurement of the respective spectral channel ratios allows for accurate spectral reconstruction and proper characterization of the incident radiation, irrespective of the angle of incidence. However, this does not apply to measurements of the total amount of incident radiation, the irradiance, or lux, which can depend strongly on the tilt angle of the device relative to the incident radiation, particularly the angle of incidence (AOI), also known as the chief ray angle (CRA) in the case of a dominant light source. This total value, characteristic of the intensity of the incident light, can be relevant for further signal processing, and the absolute value of the illuminance measurement decreases cosinally in typical detector channel designs and layouts. In particular, typical wearable or handheld devices such as smartwatches or mobile phones tend to tilt at any time, and in applications involving sol With such devices, the accuracy of the lux measurement, etc., leads to incorrect output values. In some solutions, compensation methods can be used by providing additional compensation pixel structures that capture geometric information about the inci